The Big Bang Theory co-creator Chuck Lorre admits that he misunderstood the best part of Penny (Kaley Cuoco) during the sitcom’s early episodes. Many elements in the show were revised after the unaired pilot episode, including casting Kaley Cuoco to play Penny instead of Amanda Walsh. Cuoco playing Penny is one of numerous strengths that led to the show’s long-running success, along with numerous Big Bang Theory spinoff shows.

On the first episode of The Official Big Bang Theory Podcast (via Deadline), Lorre explains that The Big Bang Theory‘s early episodes did Penny a disservice by focusing on her being a “goofy blonde who says foolish things.” He breaks down how it took him and the show’s creative team too long to realize that the best part of Penny is her intelligence and humanity that the other characters didn’t have. Lorre regrets Penny being “sadly one-dimensional” in the beginning, but is happy that this was rectified as the series progressed.